Cxcl17 is a proinflammatory chemokine and promotes neutrophil trafficking

CXCL17, a novel member of the CXC chemokine class, has been implicated in several human pathologies, but its role in mediating immune response is not well understood. Characteristic features of immune response include resident macrophages orchestrating successive and structured recruitment of neutrophils and monocytes to the insult site. Here, we show that Cxcl17 knockout (KO) mice, compared to the littermate wildtype (WT) control, were significantly impaired in peritoneal neutrophil recruitment post-lipopolysaccharide (LPS) challenge. Further, the KO mice show dysregulated Cxcl1, Cxcr2, and IL6 levels, all of which directly impact neutrophil recruitment. Importantly, the KO mice showed no difference in monocyte recruitment post LPS-challenge or in peritoneal macrophage levels both in unchallenged and LPS-challenged mice. We conclude that Cxcl17 is a proinflammatory chemokine, and that it plays an important role in the early proinflammatory response by promoting neutrophil recruitment to the insult site.

Chemokine Cxcl1-Cxcl2 heterodimer is a potent neutrophil chemoattractant

Microbial infection is characterized by release of multiple proinflammatory chemokines that direct neutrophils to the insult site. How collective function of these chemokines orchestrates neutrophil recruitment is not known. Here, we characterized the role for heterodimer and show that the Cxcl1-Cxcl2 heterodimer is a potent neutrophil chemoattractant in mice and can recruit more neutrophils than the individual chemokines. Chemokine-mediated neutrophil recruitment is determined by Cxcr2 receptor signaling, Cxcr2 endocytosis, and binding to glycosaminoglycans. We have now determined heterodimer's Cxcr2 activity using cellular assays and Cxcr2 density in blood and recruited neutrophils in heterodimer-treated mice. We have shown that the heterodimer binds glycosaminoglycans with higher affinity and more efficiently than Cxcl1 or Cxcl2. These data collectively indicate that optimal glycosaminoglycan interactions and dampened receptor activity acting in concert in a dynamic fashion promote heterodimer-mediated robust neutrophil recruitment. We propose that this could play a critical role in combating infection.

Habituation for professional learning: a qualitative study of physiotherapy students' experiences working with anatomy cadavers

INTRODUCTION

Cadaveric dissection shapes the ways in which healthcare students understand the human body and the attitudes, identities and behaviors they exhibit as health professionals. There is however a paucity of related research with physiotherapy (PT) students.

PURPOSE

The purpose of this interpretivist study was to investigate PT students' conceptions of the human body in relation to experiences with human cadavers in anatomy education.

METHODS

Ten semi-structured interviews were conducted with PT students along with four optional written reflections completed. Data was thematically analyzed.

RESULTS

Students engaged in a continuous process of habituation involving oscillation between "humanization" and "dehumanization" of cadavers in the anatomy lab. We describe the contextual mediators that shaped the process, the multi-sensory and emotional experience of the students, and the "interruptions" that contributed to the variability in their conceptions over time and contexts. Students ultimately habituated toward dehumanization which had multiple effects on learning and professionalization.

CONCLUSION

Study findings highlight the complexity of PT students' experiences and learning within the cadaver lab outside of the formal goals of anatomy education. We discuss the implications for anatomy curricula, including the potential advantages of incorporating a biopsychosocial approach.

An investigation of depression and inflammation as potential mediators linking adverse childhood experiences with cognitive decline in adulthood: results from a prospective cohort study

Introduction

Adverse childhood experiences (ACEs) have been associated with numerous health consequences in adulthood including cognitive decline. However, the underlying mechanisms implicated remain unclear.

Objectives

In this study, depressive symptoms and systemic inflammation were investigated as potential independent mediators of the association between ACEs and cognitive decline.

Methods

Participants were adults aged 50+ from the English Longitudinal Study of Ageing (N = 3,029; 54.8% female). Measures included self-reported ACEs at wave 3 (2006-2007), C-reactive protein (CRP) and depressive symptoms at wave 4 (2008-2009), and cognitive function at waves 3 and 7 (2014-2015). Mediation analyses examined the direct associations between ACEs and cognitive function at wave 7 and the indirect associations via depressive symptoms and CRP at wave 4 and were conducted using ordinary least squares regression models with the SPSS PROCESS macro. In Step 1, models were adjusted for sociodemographic factors and baseline cognitive function. Models in Step 2 were additionally adjusted for obesity and health behaviours (n = 1,874).

Results

Cumulative ACEs exposure was shown to positively predict later-life depressive symptoms, which in turn predicted cognitive decline. ACEs were also shown to positively predict systemic inflammation as measured by CRP. However, CRP did not mediate the association between ACEs and cognitive decline.

Conclusions

These findings suggest that ACEs are related to cognitive decline partly via depressive symptoms and corroborate prior research linking ACEs with adult systemic inflammation. Efforts towards screening for, preventing, and mitigating the effects of ACEs may therefore represent an important avenue for improving health outcomes in later life.

Disclosure

No significant relationships.

Genome-scale screens identify factors regulating tumor cell responses to natural killer cells

To systematically define molecular features in human tumor cells that determine their degree of sensitivity to human allogeneic natural killer (NK) cells, we quantified the NK cell responsiveness of hundreds of molecularly annotated 'DNA-barcoded' solid tumor cell lines in multiplexed format and applied genome-scale CRISPR-based gene-editing screens in several solid tumor cell lines, to functionally interrogate which genes in tumor cells regulate the response to NK cells. In these orthogonal studies, NK cell-sensitive tumor cells tend to exhibit 'mesenchymal-like' transcriptional programs; high transcriptional signature for chromatin remodeling complexes; high levels of B7-H6 (NCR3LG1); and low levels of HLA-E/antigen presentation genes. Importantly, transcriptional signatures of NK cell-sensitive tumor cells correlate with immune checkpoint inhibitor (ICI) resistance in clinical samples. This study provides a comprehensive map of mechanisms regulating tumor cell responses to NK cells, with implications for future biomarker-driven applications of NK cell immunotherapies.

Rapid signaling reactivation after targeted BRAF inhibition predicts the proliferation of individual melanoma cells from an isogenic population

Cancer cells within tumors display a high degree of phenotypic variability. This variability is thought to allow some of the cells to survive and persist after seemingly effective drug treatments. Studies on vemurafenib, a signaling inhibitor that targets an oncogenic BRAF mutation common in melanoma, suggested that cell-to-cell variation in drug resistance, measured by long-term proliferation, originates from epigenetic differences in gene expression that pre-exist treatment. However, it is still unknown whether reactivation of signaling downstream to the inhibited BRAF, thought to be a key step for resistance, is heterogeneous across cells. While previous studies established that signaling reactivation takes place many hours to days after treatment, they monitored reactivation with bulk-population assays unsuitable for detecting cell-to-cell heterogeneity. We hypothesized that signaling reactivation is heterogeneous and is almost instantaneous for a small subpopulation of resistant cells. We tested this hypothesis by monitoring signaling dynamics at a single-cell resolution and observed that despite highly uniform initial inhibition, roughly 15% of cells reactivated signaling within an hour of treatment. Moreover, by tracking cell lineages over multiple days, we established that these cells indeed proliferated more than neighboring cells, thus establishing that rapid signaling reactivation predicts long-term vemurafenib resistance.

Neutrophil recruitment by chemokines Cxcl1/KC and Cxcl2/MIP2: Role of Cxcr2 activation and glycosaminoglycan interactions

Chemokines play a crucial role in combating microbial infection by recruiting blood neutrophils to infected tissue. In mice, the chemokines Cxcl1/KC and Cxcl2/MIP2 fulfill this role. Cxcl1 and Cxcl2 exist as monomers and dimers, and exert their function by activating the Cxcr2 receptor and binding glycosaminoglycans (GAGs). Here, we characterized Cxcr2 G protein and β-arrestin activities, and GAG heparan sulfate (HS) interactions of Cxcl1 and Cxcl2 and of the trapped dimeric variants. To understand how Cxcr2 and GAG interactions impact in vivo function, we characterized their neutrophil recruitment activity to the peritoneum, Cxcr2 and CD11b levels on peritoneal and blood neutrophils, and transport profiles out of the peritoneum. Cxcl2 variants compared with Cxcl1 variants were more potent for Cxcr2 activity. Native Cxcl1 compared with native Cxcl2 and dimers compared with native proteins bound HS with higher affinity. Interestingly, recruitment activity between native Cxcl1 and Cxcl2, between dimers, and between the native protein and the dimer could be similar or very different depending on the dose or the time point. These data indicate that peritoneal neutrophil recruitment cannot be solely attributed to Cxcr2 or GAG interactions, and that the relationship between recruited neutrophils, Cxcr2 activation, GAG interactions, and chemokine levels is complex and highly context dependent. We propose that the ability of Cxcl1 and Cxcl2 to reversibly exist as monomers and dimers and differences in their Cxcr2 activity and GAG interactions coordinate neutrophil recruitment and activation, which play a critical role for successful resolution of inflammation.

Abstract PO041: Landscape of molecular events regulating tumor cell responses to natural killer cells

Natural killer (NK) cells exhibit potent activity in pre-clinical models of diverse hematologic malignancies and solid tumors and infusion of high numbers of NK cells, either autologous or allogeneic, after their ex vivo expansion and activation, has been feasible and safe in clinical studies. To systematically define molecular features in human tumor cells which determine their degree of sensitivity to human allogeneic NK cells, we quantified the NK cell responsiveness of hundreds of molecularly-annotated “DNA-barcoded” solid tumor cell lines in multiplexed format (PRISM; Profiling Relative Inhibition Simultaneously in Mixtures approach), correlating cytotoxicity scores for each cell line with the CCLE transcriptional data (RNA-seq), to reveal genes that are associated with resistance or sensitivity to NK cells. In addition, we applied genome-scale CRISPR-based gene editing screens in several solid tumor cell lines to interrogate, at a functional level, which genes regulate tumor cell response to NK cells. Based on these orthogonal studies, NK sensitive tumor cells tend to exhibit high levels of the NK cell-activating ligand B7-H6 (NCR3LG1); low levels of the inhibitory ligand HLA-E; microsatellite instability (MSI) status; high transcriptional signature for chromatin remodeling complexes and low antigen presentation machinery genes. Treatment with an HDAC inhibitor reduced the sensitivity of SW620 colon cancer cells, increased antigen presentation machinery, including HLA-E, and reduced B7-H6. Importantly, we observe that transcriptional signatures of NK cell-sensitive tumor cells correlate with immune checkpoint inhibitor resistance in clinical samples. Strikingly, comprehensive analysis of the CCLE transcriptional signatures revealed that cell lines with mesenchymal-like program tend to be more sensitive to NK cells treatment, compared with cell lines of epithelial-like program. Indeed, mesenchymal tumors tend to have lower expression of antigen presentation machinery in both CCLE and TCGA, suggesting a link between these two machieneries. This study provides a comprehensive map of mechanisms regulating tumor cell responses to NK cells, with implications for future biomarker-driven applications of NK cell immunotherapies.

Citation Format: Michal Sheffer, Emily Lowry, Nicky Beelen, Minasri Borah, Suha Naffar-Abu Amara, Chris C. Mader, Jennifer Roth, Aviad Tsherniak, Olga Dashevsky, Sara Gandolfi, Samantha Bender, Jordan Bryan, Cong Zhu, Li Wang, Ricardo De-Matos Simoes, Channing Yu, Yiguo Hu, Olli Dufva, Marios Giannakis, Todd Golub, Rizwan Romee, Satu Mustjoki, Aedin C. Culhane, Lotte Wieten, Constantine S. Mitsiades. Landscape of molecular events regulating tumor cell responses to natural killer cells [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO041.

A randomized phase III trial of active symptom control (ASC) with or without chemotherapy in the treatment of patients with malignant pleural mesothelioma: First results of the Medical Research Council (MRC) / British Thoracic Society (BTS) MS01 trial

LBA7525

Background: Although chemotherapy is widely used in the treatment of mesothelioma it has never been compared in a randomized trial with ASC alone. Two chemotherapy regimens that had shown good symptom palliation in phase II studies were chosen for investigation. Methods: Patients with malignant pleural mesothelioma were randomized to ASC alone (regular follow-up in a specialist clinic, and treatment could include steroids, analgesics, bronchodilators, palliative radiotherapy, etc), ASC+MVP (4 × 3-weekly cycles of mitomycin 6g/m2, vinblastine 6mg/m2, and cisplatin 50mg/m2), or ASC+N (12 weekly injections of vinorelbine 30mg/m2). 420 patients were required to detect a 3-month improvement in median survival with ASC+CT (both chemotherapy arms combined). Quality of Life (QL) was assessed using the EORTC QLQ-C30. Results: 409 patients were accrued (136 ASC, 137 ASC+MVP, 136 ASC+N). Median age: 65 years, male: 91%, Performance status 0: 23%, Epithelial histology: 73%, Stage III: 33%, Stage IV: 48%. In the ASC+MVP group 61% received all 4 cycles, and in the ASC+N group 49% received at least 10 weekly cycles. Good symptom palliation (defined as prevention, control or improvement) was achieved in all 3 groups, and no between-group differences were observed in 4 pre-defined QL subscales (physical functioning, dyspnoea, pain and global QL). A small (not conventionally significant) survival benefit was seen for ASC+CT (349 deaths, HR 0.89, 95%CI 0.72, 1.12, p=0.32). Median survival: ASC: 7.6 months, ASC+CT: 8.5 months. Exploratory analyses suggested a survival advantage for vinorelbine compared to ASC alone (HR 0.81, 95%CI 0.63, 1.05, p=0.11), with a median survival of 9.4 months, but no evidence of a benefit with MVP (HR 0.98, 95%CI 0.76, 1.28), p=0.91). Conclusions: This is the 2nd largest ever randomized trial in mesothelioma and the first to compare ASC with or without chemotherapy. Although the addition of chemotherapy to ASC did not result in a conventionally significant survival benefit, there was an indication that vinorelbine should be investigated further, and that MVP probably has no role in this disease.

[Table: see text]

Cardiac exposure history as a determinant of symptoms and emergency department utilization in noncardiac chest pain patients

Although comparative studies differentiate noncardiac chest pain (NCCP), panic disorder, and coronary artery disease (CAD), little research has examined the defining features of NCCP, such as cardiac complaints, medical utilization, and learning history. We administered self-report measures to 80 Emergency Department (ED) patients with a primary complaint of chest pain who were subsequently found to not have CAD. Forty-eight percent of the ED utilization variance was accounted for by NCCP duration, age, cardiac distress symptoms, and prior exposure to both siblings' and friends' cardiac distress symptoms. In turn, 67% of the variance in cardiac distress symptoms was explained by education, age, NCCP duration, number of illnesses, noncardiac panic symptoms, prior exposure (friends), and prior observation of others' cardiac distress. No effects emerged for gender, ethnicity, avoidance, or depression. Results suggest that beyond the effects of age and distress intensity, prior exposure to other people's cardiac distress may influence NCCP.

Improving surgical resection rate in lung cancer

BACKGROUND

Surgical resection is the recognised treatment of choice for patients with stage I or II non-small cell lung cancer (NSCLC). In the UK surgical resection rates have remained far lower (< 10%) than those achieved in Europe and the USA (> 20%), despite the recent introduction of fast access investigation units. It remains unclear therefore why UK surgical resection rates lag so far behind those of other countries.

METHODS

A new quick access two stop investigation service was established at Papworth in November 1995 to investigate all patients presenting to any of three surrounding health districts with suspected lung cancer. Once staging was complete, all patients with confirmed lung cancer were reviewed by a multidisciplinary team which included an oncologist and a thoracic surgeon. Time from presentation to definitive treatment and surgical resection rates were reviewed.

RESULTS

Two hundred and nine (76%) of a total of 275 consecutive patients investigated had confirmed lung cancer (28 small cell, 181 non-small cell). Of the remainder, eight patients (2%) had metastatic disease, four (1%) had other thoracic malignancy (thymoma, mesothelioma), four patients (1%) had benign thoracic tumours, and 50 (18%) had other non-malignant diseases. Of the 181 patients with non-small cell primary lung cancer, 47 (25%) underwent successful surgical resection, of whom 59% had stage I and 21% stage II disease. The failed thoracotomy rate was 11%. Median time from presentation at the peripheral clinic to surgical resection was 5 weeks (range 1-13).

CONCLUSION

Quick access investigation, high histological confirmation rates, routine CT scanning, and review of every patient with confirmed lung cancer by a thoracic surgeon led to a substantial increase in the successful surgical resection rate. These results support the growing concern that many patients with operable tumours are being denied the chance of curative surgery in our present system.

Transcranial Doppler blood flow velocity versus 133Xe clearance cerebral blood flow during mild hypothermic cardiopulmonary bypass

OBJECTIVE

Transcranial doppler (TCD) is used during cardiopulmonary bypass (CPB) to assess cerebral emboli and to estimate cerebral perfusion. We sought to compare TCD middle cerebral artery blood flow velocity (Vmca) to 133Xe clearance cerebral blood flow (CBF) measurements during mild hypothermic CPB thus determining its utility in cerebral perfusion assessment.

METHODS

Thirty-four patients undergoing mild hypothermic CPB (35 degrees C) were studied and had comparisons of Vmca and 133Xe CBF at three time intervals, 10, 30 and 60 min after the institution of CPB. Linear regression analysis was performed on data from each of the 3 intervals as well as for pooled data from all 3 periods.

RESULTS

The correlation coefficients for the 3 time periods were, r = 0.32 (p = 0.12), r = 0.32 (p = 0.11), r = 0.48 (p = (0.02), respectively. The pooled data correlation had a coefficient of 0.34 (p = 0.003).

CONCLUSION

These findings suggest that TCD Vmca is a relatively poor correlate of CBF during mild hypothermic CPB.

Continuous jugular venous versus nasopharyngeal temperature monitoring during hypothermic cardiopulmonary bypass for cardiac surgery

STUDY OBJECTIVE

To compare jugular venous to nasopharyngeal temperature during hypothermic cardiopulmonary bypass (CPB).

DESIGN

Prospective observational study.

SETTING

Tertiary care teaching hospital.

PATIENTS

5 ASA physical status IV patients (40 to 65 years of age) having cardiac surgery with hypothermic CPB. INTERVENTIONS, MEASUREMENTS AND MAIN RESULTS: Jugular venous and nasopharyngeal temperatures were recorded throughout the procedure with comparisons made during four time periods: pre-CPB, during CPB, during rewarming, and post-CPB. The patients underwent 85.8 +/- 45.8 minutes (mean +/- SD) of hypothermic CPB, cooling to 26.3 +/- 7.6 degrees C (nasopharyngeal) followed by rewarming at 0.35 +/- 0.1 degree C (nasopharyngeal)/min. There was a high degree of precision between the two temperature sites, but marked differences in bias. In particular, temperature bias was more pronounced during rewarming from CPB compared with other time periods (p < 0.05) where jugular venous temperature was greater than nasopharyngeal temperature by 3.4 degrees C.

CONCLUSION

Nasopharyngeal temperature underestimates jugular venous temperature during rewarming from hypothermic CPB. As a result, the brain may be exposed to periods of hyperthermia, possibly increasing the risk of neurologic injury associated with CPB.

Effect of temperature during cardiopulmonary bypass on gastric mucosal perfusion

The purpose of our study was to prospectively study the splanchnic response to hypothermic and tepid cardiopulmonary bypass (CPB) using alphastat management of arterial blood-gas tensions. Twenty-four patients for elective CABG surgery were allocated randomly to tepid (35-36 degrees C) or hypothermic (30 degrees C) bypass groups. Measurements were made at four times: (1) baseline, (2) stable during CPB (inflow temperature = nasopharyngeal temperature) 30 degrees C for hypothermic patients, bypass +20 min for tepid patients, (3) 10 min before the end of bypass, (4) after bypass, skin closure. Both groups demonstrated a significant reduction in gastric intramucosal pH (pHim) from time 1 to time 4 and there was no difference in the incidence of a low pHim between the tepid and cold groups (4/12 vs 3/12; ns) at time 4. pHim was significantly lower in the tepid groups at time 3 (P = 0.03) but this discrepancy may have been because of an artefactually high pHim in the cold group. There was a significantly higher incidence of postoperative non-cardiac complications in patients who had a low pHim at time 4 (P = 0.0008). Therefore, we conclude that although the temperature during CPB had a transient effect on pHim it is unlikely to be a major determinant in the pathogenesis of gut mucosal hypoperfusion after bypass.

Effect of perfusion pressure on cerebral blood flow during normothermic cardiopulmonary bypass

BACKGROUND

We have recently shown that during hypothermic cardiopulmonary bypass (CPB), cerebral autoregulation has a positive slope such that for every 10 mm Hg change in pressure, a 0.86 mL.100 g-1.min-1 change in cerebral blood flow (CBF) is predicted. The purpose of this study was to define the influence of mean arterial blood pressure (MAP) on CBF during normothermic CPB.

METHODS AND RESULTS

CBF was measured by use of 133Xe washout and alpha-stat blood gas management during nonpulsatile CPB. CBF measurements were made at a pump flow of 2.4 L.min-1.m-2 at stable normothermia and approximately 15 minutes later after the MAP was increased or decreased > or = 20%. A third data set was recorded after the pressure was returned to the initial value. Forty-five patients were entered into the study. Temperature was held constant. We found a significant effect (P = .016) of change in MAP on change in CBF during normothermic CPB. For a 10 mm Hg increase in MAP, an increase in CBF of 1.78 mL.100 g-1.min-1 is predicted. Along with change in CBF, significant increases in both cerebral metabolic rate and cerebral oxygen delivery were observed.

CONCLUSIONS

This information, along with our previous data shows that autoregulation during CPB has a positive slope that is greater with normothermia than hypothermia. Although it is unlikely that these small changes in flow are an important primary effect in the development of hypoperfusion, increased metabolic rate with increased CBF may indicate pressure-dependent collateral flow potentially in regions embolized during CPB.

Predictors of cognitive decline after cardiac operation

Despite major advances in cardiopulmonary bypass technology, surgical techniques, and anesthesia management, central nervous system complications remain a common problem after cardiopulmonary bypass. The etiology of neuropsychologic dysfunction after cardiopulmonary bypass remains unresolved and is probably multifactorial. Demographic predictors of cognitive decline include age and years of education; perioperative factors including number of cerebral emboli, temperature, mean arterial pressure, and jugular bulb oxygen saturation have varying predictive power. Recent data suggest a genetic predisposition for cognitive decline after cardiac surgery in patients possessing the apolipoprotein E epsilon-4 allele, known to be associated with late-onset and sporadic forms of Alzheimer's disease. Predicting patients at risk for cognitive decline allows the possibility of many important interventions. Predictive power and weapons to reduce cellular injury associated with neurologic insults lend hope of a future ability to markedly decrease the impact of cardiopulmonary bypass on short-term and long-term neurologic, cognitive, and quality-of-life outcomes.

Occurrence and frequency of subgroup I-6 spiroplasma in arthropods associated with old fields in Maryland and Virginia

The Subgroup I-6 spiroplasma, "Maryland Flower Spiroplasma," originally discovered on fall flowers and subsequently recovered from a syrphid fly and a beetle triungulin, was isolated from two new fall flower hosts and from the guts of nine nectar-imbibing insect species. These data, together with lack of recovery of I-6 spiroplasma from foliage-feeding, plant-sucking, or flightless flower-associated insects, suggest that I-6 spiroplasma may infect and be disseminated by nectar- or pollen-foraging insects, and that the dynamics of maintenance will prove to be complex.